Hydraulic casing driver



NOV. 8, 1955 E, MERTEN HYDRAULIC CASING DRIVER Filed NOV. 19, 195] INVENTOR:

E UGEN MERTEN HIS ATTORNEY United States PatentOfiiice 2,723,106 Patented Nov. 8, 1955 HYDRAULIC CASING DRIVER Application November 19, 1951, Serial No. 257,094

Claims. c1. zss 4.4

This invention relates to well drilling equipment and pertains more particularly to a lightweight hydraulic ram motor or casing driver for use in inserting lightweight casing in shotholes during seismic surveying operations.

Seismic explorations are at times carried out on rough terrain which is impassable to trucks on which motordriven shothole drilling equipment is normally mounted, and in such cases shotholes must be drilled and easing set by hand, a time-consuming operation especially when it is necessary to drill into hard formations.

It is a primary object of the present invention to provide a lightweight hydraulic ram motor adapted to be employed with hand-operated rotary drilling equipment for drilling shotholes and setting casing therein.

A further object of this invention is to provide a'hydraulic ram motor detachably insertable in lightweight casing for driving said easing into a borehole and removable therefrom after said casing is in place.

It is a particular object of the present invention to provide for this purpose a combination comprising a ram motor of the general type described in my Patent No. 2,424,108. Another object of this invention is to provide a portable hydraulic ram motor, operated by waterhammer effect, which prevents shock waves from being transmitted upwardly through a drill string or casing in which the ram motor is positioned.

These and other objects of the present invention will be understood from the following description with reference to the attached drawing which shows an embodiment of the present casing driver in longitudinal cross section while positioned in a section of shothole casing.

Referring to the drawing, a section of lightweight shothole casing is illustrated as having a drag bit 11 attached to the lower end thereof. The upper end of the casing 10 is provided with a threaded portion 35 to which additional length or sections of easing may be added. Coaxially positioned within the casing 10 is the present casing driver whose lower end 12 is seated within the top of the bit 11. The inner wall of the bit is preferably tapered, as at 13, -or slopes inwardly to form a tapered seat which automatically positions the lower end 12 of the casing driver concentrically within the casing 10. Since the casing driver has an outside diameter substantially smaller than the inner diameter of the casing string 10, an-annular flow passage 14 isformed between the driver and the casing. The drill bit 11 is provided with conduit means such as one or more passages 15, for liquid circulation from within the casing 10 to the space outside the-bit. If desired the lower end 12 of the casing driver may be provided with suitable packing means, such as 'a rubber riuggasket 12a, to insure afl'uidtight seal'be'tween the casing driver and the bit.

I The casing driver comprises a tubular housing-16 closed at the upper end by a plug 17 having a fishing head formed thereon. The lower end of the casing driver is closed by a valve structure comprising 'a resilient ball valve 18 -positioned above a concave valve seat 19, said her, as by rubber plugs 27 and 28, and preferably proseat being provided with liquid passages 20 therethrough and having raised central portion 21, as shown in the drawing, or being otherwise formed so as to provide ample space for the passage of liquid between the ball valve 18 and seat 19 until the resilient ball valve is compressed against the seat, as will be described hereinbelow. The ball valve 18is made of any suitable resilient rubber or plastic material. When high water-hammer pressures are required, the material of which the ball is made should have a greater hardness in order that the ball will not be pressed into or through the passages 20.

Preferably, the raised central portion 21 of the valve seat 19 has formed therein a recess 22 adapted to receive asupporting member 23, which is elevated and protrudes above the concave upper face of the seat 19. The head of the member 23 may be fiat or of any desired convex shape. The insert member 23 is made of a material such as rubber, synthetic rubber, hard rubber, ebonite, or any other suitable resilient plastic material, it having been found that the use of any of these materials in the central portion of the seat of the valve'diminishes to a very great degree the wear on the ball 18 which is normally made 'of rubber or a plastic. The diameter of the ball valve 18 is less than that of the tubular housing 16 so that 'an annular flow passage 24 is formed between the ball 18 and the housing 16.

A major portion of the upper half of the tubular housing 16 is provided with a plurality of holes 25 through the walls thereof. Positioned within this perforate section of the tubular housing 16 is an elastic diaphragm or rubber sleeve 26 closed at both ends in a fluid-tight manvided with suitable valve means 29 through which a gas such as air may be introduced under pressure. The sleeve 26 may be held in the perforate upper section of the housing 16 in a suitable manner, as between the head 17 and a plate 30 secured within the housing by bolt means 31.

The wall-of the housing 16 is provided with a plurality 'offluid ports 32 located between the rubber shock I absorber 26 and the ball valve 18. Thus, fluid passing down the annular space 14 between the inner wall of the casing 10, and the outer wall of the housing 16 of the casing driver is permitted to enter the housing 16 and flow down the bore thereof toward the valve 18.

- In drilling a shothole for an explosive charge, the hole may first be drilled and the casing subsequently set therein with the present casing driver. Alternatively, the casing 10 may be driven into a formation as the hole is drilled in a manner described hereinbelow. A bit'll may, if desired, be secured to one end of a section of shothole casing 10 and, after the casing driver has been placed in the casing, a hose (not shown) is connected to the top end of the casing 10. The other end of the hose'is attached to a portable pump (not shown) by which water or another liquid may be pumped into the casing. Prior to insertion of the casing driver, the shock absorber 26 thereof is inflated to a pressure of approximately (20+D/2') pounds per square inch where D is the depth in feet of the hole to be drilled.

' During the drilling operation the casing may be rotated byhand as water is pumped into the casing. The water flows down the casing 10, around the spearhead 17, past the perforations 25 in the upper end of the tubular housing 16 which contains the shock absorber 26, and into the ports 32 in the casing below the shock absorber. The water must flow through the ports 32 as the lower end of the tubular housing 16 is substantially sealed against the bit 12. The flow of water continues down the bore 33 of the housing 16, past the ball valve 18, through the openings 20 in the valve seat 19 and down through the fluid ports 15 therein.

As explained in my Patent 2,424,108, the Water velocity increases as it flows through the restricted space around the ball 18 and between the ball 18 and seat 19. This produces a differential pressure, causing the ball to be compressed. As the ball is compressed, the pressure differential across it increases, and the ball compresses further over the raised central portion 21 of the valve seat. The deformation of the resilient ball valve continues until it completely covers the seat 19 and tip 21. The increase of pressure differential, as the ball moves downward, causes the valve to close very rapidly.

When the valve shuts suddenly, the water column above the valve comes to a sudden stop. The abrupt stoppage of the liquid flow creates extremely high hydraulic ram or hammer pressures. The high water-hammer pressures act on the inner surfaces 13 of the bit 11 to impact the bit sharply against the formation being drilled. Since, however, a water-hammer cycle consists of a high pressure period followed by a low pressure period, the resilient ball 18 returns to its unstressed shape during the latter period whereby it is pushed away from the valve seat 19, thus opening the passages 20.

During the instant when the ball valve 18 is momentarily closed and the high pressure wave acts downwardly against the closed lower end of the casing driver, a pressure wave develops which travels up the casing string 10. This wave would continue up the casing to the hose and pump (not shown) if the shock absorber 26 were not set in the path. As the wave passes the perforate section of the housing 16 containing the air chamber or shock absorber 25, water is forced through the holes 26 where wave energy is converted by the compression of the shock absorber 28. The shock absorber allows the pressure to be reconverted into kinetic energy sending a low-pressure dilatational wave down the stream. This low-pressure wave allows the resiliency of the rubber ball 18 and insert 23 to open the valve. The action is repeated when the fluid velocity reaches the speed required to operate the valve; the average frequency may be about cycles per second.

Upon completion of the shothole the casing 10 and bit 11 are left in place while the casing driver is removed. An overshot, of any suitable type, is lowered on aline within the casing until it latches on to the fishing head 17. The overshot and easing driver are then pulled out of the well. It may be seen that by utilizing the present casing driver, a shothole may be both drilled and cased in one operation rather than by the expensive and time-consuming conventional method of first drilling a hole, removing the drill string and then inserting the shothole casing.

I claim as my invention:

1. A hydraulic casing driver, comprising, in combination with a string of lightweight casing having a constriction at its open lower end, a tubular housing having an outside diameter less than the inside diameter of said casing, said housing being adapted to be dropped through the fluid in said casing intofixed engagement with said constriction at the lower end of said casing, said casing string forming conduit means for conducting a pressure fluid to said housing, an air chamber formed within the upper portion of said housing, said air chamber having a resilient wall member exposed to the pressure of the fluid surrounding said housing, normally open resilient valve means positioned in said housing below said air chamber, and radial port means through the walls of said housing between said air chamber and said valve means, the flow of the fluid through the casing, the radial port means and the valve means creating thereupon a flow differential across said valve means sufiicient for suddenly closing said valve means and generating a high-pressure water-hammer impulse to drive downwards the casing string engaged by. said housing.

2. A hydraulic casing driver, comprising, in combination with a string of lightweight. casing having a constriction at its open lower end, a tubular housing having an outside diameter less than the inside diameter of said casing, said housing being adapted to be dropped through the fluid in said easing into fixed engagement with said constriction at the lower end of said casing, said casing string forming conduit means for conducting a pressure fluid to said housing, an air chamber formed within the upper portion of said housing, said air chamber having a resilient wall member exposed to the pres sure of the fluid surrounding said housing, valve means through the wall of said air chamber for inflating said air chamber, normally open resilient ball valve means positioned in said housing below said air chamber, radial port means throughthe walls of said housing between said air chamber and said valve means, fishing head means secured to the top of said housing, and means lowerable through said casing string for attachment to said fishing head means for removing the casing driver from the casing, the flow of the fluid through the casing, the radial port means and the valve means creating thereupon a flow differential across said valve means sufficient for suddenly closing said valve means and generating a high pressure water-hammer impulse to drive downwards the casing string engaged by said housing.

3. A hydraulic casing driver, comprising, in combination with a string of lightweight casing having a constriction at its open lower end, a tubular housing having having an outside diameter less than the inside diameter of said casing, said housing being adapted to be dropped through the fluid in said easing into fixed engagement with said constriction at the lower end of said casing, said casing string forming conduit means for conducting a pressure fluid to, said housing, a closed resilient container forming an air chamber within the upper end of said housing, said air chamber being secured within said housing and having a resilient Wallmember exposed to the pressure of the fluid surrounding said housing, valve means in the wall of said container for inflating said container, normally open resilient ball valve means positioned in said housing below said air chamber, and radial port means through the walls of said housing between said air chamber and said valve means for admitting fluid to the bore of said housing, the flow of the fluid through the casing, the radial port means and the valve means creating thereupon a flow differential across said valve means sufficient for suddenly closing said valve means and generating a high-pressure water-hammer impulse to drive downwards the casing string engaged by said. housing.

4.v A hydraulic casing driver, comprising, in combination with a string of lightweight casing having a constriction. at its open lower end, a tubular housing having an outside diameter less than the inside diameter of said casing, said housing being adapted to be dropped through the fluid in said casing into fixed engagement with said constriction at. the lower end of said casing, said casing string forming conduit means for conducting -a pressure fluid to said housing, a rubber sleeve closed at the ends forming an air chamber within the upper portion of said housing, said air chamber having a p rtion of its wall exposed to the pressure of the fluid surrounding said housing, valve means in the container wall for inflating said container, normally open resilient ball valve means positioned in said housing below said air chamber, and radial port means through the walls of said housing between said air chamber and said valve means for admitting fluid to the bore of said housing, the flow of the fluid through the casing, the radial port means and the valve means creating thereupon a flow differcntial across said valve means sufficient for suddenly closing said valve means and generating a high-pressure water-hammer impulse to drive downwards the casing string engaged by. said housing.

5. A hydraulic casing driver, comprising, in combination witha string of lightweight casing having a con striction at its open lower end, a tubular housing having an outside diameter less than the inside diameter of said casing, whereby an annular fluid passageway is formed between said housing and said casing string, said housing being adapted to be dropped through the fluid in said casing into fixed engagement with said constriction at the lower end of said casing, said casing string forming conduit means for conducting a pressure fluid to said housing, an elongated inflated rubber sleeve closed at the ends forming an air chamber within the upper portion of said housing, a plurality of ports through the wall of said housing adjacent said rubber sleeve whereby said air chamber is exposed to the pressure of the fluid surrounding said housing, valve means in the container wall for inflating said nlbber sleeve, normally open resilient ball valve means positioned in said housing below said air chamber, and radial port means through the walls of said housing between said air chamber and said valve means for admitting fluid to the bore of said housing, the flow of the fluid through the casing, the radial port means and the valve means creating thereupon a flow differential across said valve means suflicient for suddenly closing said valve means and generating a high-pressure water-hammer impulse to drive downwards the casing string engaged by said housing.

References Cited in the file of this patent UNITED STATES PATENTS 

